A technique is known to illuminate a combined white color light to improve color reproduction for a liquid crystal display by utilizing multiple light sources, which illuminate different colors (red (R), green (G), blue (B) and so on) as a backlight source. An example of this technique is disclosed in Japanese patent publication No. H11-295689.
FIG. 8 is a block diagram of a display device in accordance with the related art. The configuration is the same as the one disclosed by Japanese patent publication No. JPH11-295689. In this conventional display device, a feedback control technique is adopted to maintain the value of a light emission amount equal to a predetermined value by detecting the light emission amount from multiple light sources, so as to maintain the white balance set at the time of shipment or user setting, regardless of temperature variation or other time dependent variation.
A known technique to illuminate a liquid crystal element includes driving multiple light sources, which illuminate different colors (red (R), green (G), blue (B) and so on), sequentially on a time division basis. An example of this technique is disclosed in Japanese patent publication No. 2001-235729.
The technique disclosed in Japanese patent publication No. H11-295689 is able to provide a liquid crystal display device with fine color reproduction regardless of variations in environmental temperature.
White color is generated by illuminating multiple different color light sources simultaneously in Japanese patent publication No. H11-295689. Accordingly, multiple photo detectors are required to detect a light emission amount corresponding, respectively, to each color of the light sources. Furthermore, multiple operation circuits for feedback control are required corresponding to each of the light sources. This results in an increase of device size or cost.
In addition, a technique to generate white light by driving multiple light sources sequentially is disclosed in Japanese publication No. JP2001-235729. In particular, a technique is disclosed to control an illumination period corresponding to a variation of ambient temperature, against a delaying caused in a low temperature circumstance. However, there is no disclosure about a technique to adjust a white balance in view of a temperature variation or a time dependent variation of the light sources themselves.